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logicerr last won the day on August 24 2010

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About logicerr

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  1. Believe it or not, faxes. You know that tone faxes make when they dial out? Try generating that, they'll magically turn into a fax carrier. There's loads of these out there for some reason. Huh, interesting. Is that ancient faxes, or reasonably-modern-but-unusual faxes?
  2. Maybe this is a good place to get help identifying different numbers. 15098846923 MARK weird beepy thing 15098842710 MARK weird beepy thing Both numbers do the same thing: ring normally a few times, then start making what I think is supposed to sound like a ring, but really just sounds like some beeping. Then there are some high-pitched tones, then it hangs up. I see these all the time, I have no idea what they are. 15098844752 MARK "This is the district autodialer, kit key 1 for alarms * to acknowledge # to exit" Sounds like it might be interesting. Recording is low-quality and hard to understand, I might not have transcribed it right. Sounds like some hacked-together thing. I also find a lot of modems that answer with "REMOTE nnnnn" with the n's being some digit. I would love to know what these are, I see them all the time. They stay connected for about sixty seconds, and then disconnect. Sometimes just before the call is ended it sends "AT" like it's not waiting long enough before sending the modem commands, and also strongly suggesting is a modem that takes AT commands rather than some embedded thing. Here's a log of one: ATDT 15098840697 CONNECT 9600/ARQ/V34/LAPM REMOTE 45941 AT NO CARRIER I know it's probably not anything terribly interesting, but it's been gnawing at me.
  3. So, more updates. The boards and components arrived. I assembled my modem board and attached it to my microcontroller proto-board, loaded my code, and as I expected somethings not quite right. When I request the modem's ID it consistently gives me a response that doesn't match what I should be getting, or any obvious mutation of it. I'll have to wait until classes start again so I can watch what's happening on a logic analyzer. I'm still pretty happy with the way things are progressing. With any luck I'll have the board working within the next few weeks so I can get started on the first uC/modem combo board and start using the thing in the real world. If I can afford to build a few I'd love to send a few out to different people who are interested in trying them out.
  4. From the link it looks like you're talking about remote ring? The modem will detect call progress, but relies on us to know if there's an inbound call so we can issue a command to open the line. That's what I meant, sorry. I didn't consider that "ring" was ambiguous. Still really cool information, though. As an aside, when messing around locally I sometimes find lines that have a really odd ring. It's hard to explain, and I don't have a number on hand as an example, but it's much lower pitched than a normal ring, and I used to mistake them for TTYs when I wasn't paying enough attention. This probably isn't enough info for identification, but it's all I can come up with right now. I always assumed it was a weird PBX or something. If it's helpful, I live in the northwestern United States. I think you do too. I'd like to add some way to charge from the line eventually. Maxim has an appnote about it here. Adding this circuit would more than triple my parts count though. It says it should provide about 150mW when off-hook, that's about twice what the board should use when in a call. It would also be useful to be able to do some simple tone detection. There are a lot of interesting things to find that aren't modems, and I think signatures could be made for most of them. Unfortunately the AVR isn't powerful enough to do any real tone detection work. I'd also like to write some sort of simple scripting language, so a program could be "uploaded" to the chip and then run. I'd want it to be easy enough to write so people could get in to it pretty easily. Since the modem can generate DTMF, including A-D, it could do something like call in to a voicemail and wait a set period before it spat out anything we wanted it to report. Two DTMF tones could correspond to one hexadecimal digit. These are all ideas I've been playing with. If you want to see the capabilities of the chip, the most current revision of the datasheet is here: http://www.teridian.com/products/secure-access-networking/modem--sidaa/222al222bl.php Keep the ideas coming. I'd hate to come up with a fantastic idea that I wish I'd included just after I send the next boards out for processing.
  5. Hope it's not out of line to create a new topic for this. I posted a thread a couple months ago asking for some advice on my project, and some really good information. Thanks for that. I thought some of you might be interested in how the project is progressing. I just ordered the components for an initial development board sort of thing today. After sifting through quite a few documents I finally settled on using a 73K222BL as the modem. 73K222 is apparently just a 73K212 with some revisions, and the BL will control opening the line itself, while the AL relies on the uC to do this. There are probably some benefits to having the line under software control, but I decided not to for this application. We can still open and close the line with commands to the modem, but probably not fast enough for something like pulse dialing. I'm using an LH1546 optocoupler to open and close the line. The 73K222BL (and all the other modems in the series) apparently aren't manufactured anymore, so I had to source them from a shady Chinese operation. The rest of the components are coming from some well-known US-based suppliers. I didn't quite make my ~$20/unit price goal, but that may have been unrealistic. I'm still not doing to bad considering my small orders. Building them in a reasonably quantity might get them close to $20. They're still cheap enough that I can treat them as disposable if a situation warrants it. I didn't want to deal with working with a PLCC on a breadboard, so I decided to go straight to making a simple development board. My modem development board will attach to an off-the-shelf uC development board so I can start working. The PC boards have been set up, and the designs were sent off for manufacture today. The turnaround is slow, I can probably expect them to be here in about a month. If the boards aren't fantastically fucked up I can start testing some of my code then. These modem board can't power themselves yet (they rely on the uC board for power,) and they'll be tedious to attach to anything other than the uC development board I designed them for, so they're definitely not ready for being out in the wild, but I'm still making progress. If things go well I might have a fully integrated board with in-system programming, etc within the next few months. The uCs I'm using are Atmel AVR series, probably ATMEGA8. You can probably think of some applications of a low-power programmable controller+modem pretty quickly, and a few more interesting ones if you keep it in mind for a little while. Once things start looking a bit more respectable I'd love to publish what I've come up with so others here can experiment if they're interested. I can recall a time when I was younger (and a bit more active in working with phones) when a battery-powered, programmable board like the one I'm hoping for would have been the holy grail. Hopefully I'm getting close to satisfying the curiosity of my inner-troublemaker.
  6. Interesting about the pulse dialing.. Maybe because it ends up looking like an AC signal somehow? That FSK appnote is cool as hell. I am using the AVR, so I could probably use the ADC to look at zero crossings, but the math to get that done is way beyond me right now.. I've seen the code but I don't nearly understand it. I'd also considered looking for specific tones with some simple external hardware, but I'd have to work with a finite set of tones, and I'm not sure what exactly I would look for. What would you guys say would take priority? And faxes would also get marked positive for the connect tone.. Not that it would be so difficult to weed them out. Around here it's probably about 10 fax machines to 1 data modem. It turns out I actually have a 73K212AL kicking around the house. It's in an old Z80-based credit card terminal that I was messing with, but I might remove it to play with it. The modems I ordered should get here in the next few days, too. I've been working on the code to get things started. I think it should be easy enough to generate DTMF, so I'll probably just do that. That also gives me an easy way to report numbers that connected. Could leave a list as a message in a voice mail or something similar. I'll keep working on my code for the MC145443s in the mail. It's reasonably modular, so adding support for new modems shouldn't require a total re-write. Once I get the basics working, is there a toll free range you'd recommend testing it on? That's still probably pretty far off, but it doesn't really stop me from thinking about it.
  7. Thanks for the advice, guys. I guess dialing in pulse makes sense. I'd also like to leech some power from the line, but I can't find a circuit that I'm confident will do this well in less than 15+ parts.. That chip does look good. I have some of the ICs I mentioned in my first post on the way already, but if I get some extra cash I'll pick up some of those too. Progress is a bit slow for various reasons but I'll keep you updated.
  8. Thanks for the replies! I expected some trouble using that speed and modulation. The long term goal for this thing is to have it scan for modems and report back somehow with the results. I'm hoping it works well enough to find some good stuff, but I don't expect it to work flawlessly. My goals are to keep it reasonably low-power so it can operate on batteries and keep the cost low enough for it to be considered disposable, so that rules out a lot of other potentially good solutions. I'd like to keep the parts for each one under $25, and the micro is about $3. I'd be fine with a DIP or a PLCC, but I can't find that chip anywhere.. There are a few eBay listings for a 73K212, but I can't find a datasheet for it to confirm that it's similar enough to use. It would be nice, too, because it will generate DTMF and do a few other things that would allow me to be lazy. I really appreciate the advice. I lack the real-world knowledge needed to evaluate how well it might work, so I'm glad there are people willing to help me out. Also, if one day I'm a bad enough dude to know the ICs in payphones well enough suggest them off the top of my head in various semi-related applications I'll be 100% satisfied in every aspect of my life.
  9. I'm working on a microcontroller-based dialer. The modem I'd like to use is a single chip device. Datasheet is here if you're interested.. http://www.futurlec.com/Motorola/MC145443P.shtml It uses a Bell 103 modulation and connects at 300 baud. Will this thing be able to connect to any modems in the wild? I know some modems will still connect at 300 baud, but how many? I'm not asking you to read the datasheet and tell me how to connect. My question is weather or not I'll be able to connect to much at 300 baud using Bell 103. Thanks guys.
  10. Well, I lurk around this form a lot, but this is my first ever post. I was pumping my gas today, and I got to wondering how gas pumps communicate with the attendants, banks, etc. Certainly the protocols would differ from pump to pump, but I was wondering if anyone had any expirence in this? Google and Wikipeida yeild little information.